There are known devices and methods for correction of acoustic parameters of electro-acoustic transducer by using measurements of acoustic parameters of electro-acoustic transducers where correction is performed both automatically and with participation of sound operator. Disadvantage of the known technical solutions is relatively low precision of measuring and poor quality of correction results.
It is known that human ear perceives information about sound timbre from direct sound, namely, the sound coming directly from acoustic transducer and early reverberation of the sound that reaches listener in first 30 ms after direct sound but ignores other sound reverberation. Up to now used measuring devices do not differentiate and separate direct sound waves and early reverberation of sound waves from posterior reverberation of sound waves.
The conventional technical solutions for correction of acoustic parameters of electro-acoustic transducer that are based on evaluation results of sound pressure caused by electro-acoustic transducer do not reflect real problems of playback of electro-acoustic transducer. Also, sound pressure frequency responses vary greatly depending on where the sound pressure caused by the electro-acoustic transducer is evaluated. Hence, the operator using the conventional technical solution faces an insoluble problem of having to select which of acquired sound pressure frequency responses to be used and which of parameters additionally to be corrected manually or to be processed differently. Because there is no specified algorithm for obtaining correction, this process starts to resemble art. Furthermore, using these measuring results for correction of acoustic parameters of electro-acoustic transducer, new sound distortions are created because there is attempt to correct the interference expression of sound waves in certain place of the room in known technical solutions. Thus, that kind of correction of acoustic parameters of electro-acoustic transducer is incorrect and inadequate to eliminate the transmission distortions and irregularities of electro-acoustic transducer.
There is known method of measuring the parameters of loudspeaker, as described in U.S. Pat. No. 4,209,672 to Nitta et al. (issued Jun. 24, 1980, entitled “Method and apparatus for measuring characteristics of a loudspeaker”, IPC H04R 29/00), according to which the measuring result of a perceived sound parameters is transformed from analogue form to a digital form. The acquired result is exposed to the Fourier Transform, afterwards modified into absolute value, logarithmed and further filtered in order to eliminate the effect of interference and thus to increase the accuracy of loudspeaker parameters' measurements. Finally, the acquired result is transformed into analogue form and written in memory accordingly, hereto the acquired result is being written repeatedly by back playing the test signal from the generator in certain time interval. Disadvantage of the given method lies in the fact that the measurements used for adjustment do not reflect the sound distortions of the electro-acoustic system and filtration process does not differentiate sound distortions created by the electro-acoustic system from the ones created by the room. Thus, the calculated adjustment is inaccurate and the result of adjustment creates worse sound than before its making.
An acoustic signal correction device is described in U.S. Pat. No. 5,581,621 to Koyama et al. (issued Dec. 3, 1996, entitled “Automatic adjustment system and automatic adjustment method for audio devices”, IPC H03G 5/00). The device contains memory device for equalizer data keeping, audio device with programmable equalizer that selectively modifies audio signal accordingly to the equalizer data, and the audio signal analyzer that generates bench signal which keeps in its memory a pattern profile of the preferable frequency response to which the audible sound output signal is being compared. Hereto, the signal analyzer is connected to programmable equalizer and audio device, but audio device generates audible sound signal according to bench signal. Besides, the acoustic signal correction device contains tools for automatic equalizer data correction according to collation results. Memory device keeps in memory frequency response pattern profile and adjustment results. Equalizer also contains tools that divide output signal into sub-ranges of many frequencies. Disadvantage of the given range lies in the fact that the measurements used for the correction of acoustic signals do not reflect the sound distortions of electro-acoustic system, the result of adjustments creates worse sound than before their making.
The technical solution described in EP 0 624 947 B1 to Yamaha Corporation (granted Aug. 27, 2003, entitled “Acoustic characteristic correction device,” IPC H03G 5/16) is an acoustic characteristic correction device consisting of:                Measuring block that includes Measuring Section consisting of: Signal Source with test signals written in memory, amplifier, playback device, measuring device, amplifier of tested signal, registrar that fixes received signals from the mentioned measuring device as well as includes processing part for determination of correction parameters; and        Correction block that includes Control Section with correction parameters written in memory and Realization Block for entering the required parameters.        
Optimal parameters for concrete needs are supplied by making correction in zones, dividing frequency range in zones, wherein one end of the zone covers beginning of others. Disadvantage of the known device lies in its limited functional options, insufficient measurement precision of electro-acoustic transducer and relatively bad sound of corrected playback signal. The relatively bad sound of corrected playback signal is related to the fact that the correction characteristics are defined inaccurately. The reasons are as follows: Firstly, the measurements used for correction of acoustical signals do not display real problems of sound quality perceived by the listener. Secondly, adequate correction parameters are evaluated subjectively by participation of operator that causes doubts about the objectivity of correction And, thirdly, the known technical solution divides frequency range into relatively broad zones that decrease the number of samples on the frequency axis, thus losing information about the change in characteristics of frequency response on the frequency axis.